Hydraulic control system for controlling a moveable device

Abstract

A control system for controlling a moveable device includes at least one hydraulic actuator associated with the moveable device, at least one position sensing device to determine the position of the moveable device or the actuator, or both, and a hydraulic control system, including an electronic control unit, for controlling the actuator. For performing a control method, the hydraulic control system is configured to deliver pressurized hydraulic fluid to the actuator, the hydraulic fluid being pressurized at most to a predetermined maximum pressure, and the control system is adapted to regulate the predetermined maximum pressure based on the determined position. According to an example, the moveable device is a boom of a working machine. According to a further example, the actuator is a hydraulic cylinder or motor.

What is claimed is: 
     
       1. A control system for controlling a moveable device, comprising:
 at least one hydraulic actuator associated with the moveable device for performing at least one work function, wherein the moveable device is movable into several basic positions and at least one retracted position, wherein when retracted a reach of the moveable device is less than when in the basic positions; 
 at least one position sensing device to determine the position of at least one of the moveable device and the hydraulic actuator; and 
 a hydraulic control system, including an electronic control unit, for controlling the hydraulic actuator, wherein the hydraulic control system is configured to deliver pressurized hydraulic fluid at a pressure to the hydraulic actuator, the hydraulic fluid being pressurized at most to a predetermined maximum pressure, and wherein the control system is adapted to regulate the predetermined maximum pressure to be lower in the retracted position than in the basic positions. 
 
     
     
       2. The control system according to  claim 1 , wherein the hydraulic actuator is one of a hydraulic linear actuator and a hydraulic rotary actuator connected to the moveable device; and
 wherein the hydraulic actuator is adapted to one of rotate the moveable device about an axis and to linearly move the moveable device. 
 
     
     
       3. The control system according to  claim 2 , wherein the moveable device is movable into several positions such that the reach of the moveable device is dependent on the positions, wherein the control system is adapted to regulate the predetermined maximum pressure on the basis of the reach. 
     
     
       4. The control system according to  claim 1 , wherein the moveable device is movable into several positions such that the reach of the moveable device is dependent on the positions, wherein the control system is adapted to regulate the predetermined maximum pressure on the basis of the reach. 
     
     
       5. The control system according to  claim 4 , wherein the shorter the reach is the lower the regulated predetermined maximum pressure is. 
     
     
       6. The control system according to  claim 4 , wherein the longer the reach is the higher the regulated predetermined maximum pressure is. 
     
     
       7. The control system according to  claim 1 , wherein the shorter the reach is the lower the regulated predetermined maximum pressure is. 
     
     
       8. The control system according to  claim 1 , wherein the moveable device is movable into several basic positions and at least one extended position, wherein when extended the reach of the moveable device is longer than when in the basic positions, wherein the control system is adapted to regulate the predetermined maximum pressure to be higher in the extended position than in the basic positions. 
     
     
       9. The control system according to  claim 8 , wherein the longer the reach is the higher the regulated predetermined maximum pressure is. 
     
     
       10. The control system according to  claim 1 , wherein the moveable device is one of an articulated boom and a boom section of the articulated boom. 
     
     
       11. The control system according to  claim 1 , wherein the control system further comprises at least one directional control valve device with pressure reducing functions controlling the flow of the pressurized hydraulic fluid to the hydraulic actuator, wherein the directional control valve device is regulated by the electronic control unit in accordance with the predetermined maximum pressure. 
     
     
       12. The control system according to  claim 1 , wherein the control system further comprises at least one variable displacement hydraulic pump device with load-sensing functions adapted to supply the hydraulic actuator with the pressurized hydraulic fluid, wherein the hydraulic pump device is regulated by the electronic control unit in accordance with the predetermined maximum pressure. 
     
     
       13. The control system according to  claim 1 , wherein the position sensing device includes a sensor adapted to transmit a signal indicative of one of the position of the moveable device and the hydraulic actuator. 
     
     
       14. A working machine vehicle, comprising:
 a moveable device, the moveable device being one of an articulated boom and a boom section of the articulated boom connected to the working machine vehicle; and
 a control system for controlling the moveable device, the control system having: 
 at least one hydraulic actuator associated with the moveable device for performing at least one work function, wherein the moveable device is movable into several basic positions and at least one retracted position, wherein when retracted a reach of the moveable device is less than when in the basic positions; 
 at least one position sensing device to determine at least one of the position of the moveable device and the hydraulic actuator; and 
 a hydraulic control system, including an electronic control unit, for controlling the hydraulic actuator, wherein the hydraulic control system is configured to deliver pressurized hydraulic fluid at a pressure to the hydraulic actuator, the hydraulic fluid being pressurized at most to a predetermined maximum pressure, and wherein the control system is adapted to regulate the predetermined maximum to be lower in the retracted position than in the basic positions. 
 
 
     
     
       15. The working machine vehicle according to  claim 14 , wherein the working machine vehicle is one of a forestry harvester, a forestry forwarder, an agricultural tractor, a working machine equipped with a backhoe or a front end loader, a construction equipment vehicle and an excavator. 
     
     
       16. A method of controlling a moveable device by using a hydraulic control system having an electronic control unit, the method comprising:
 performing a work function with the moveable device controlled by at least one hydraulic actuator associated with the moveable device, wherein the moveable device is movable into several basic positions and at least one retracted position, wherein when retracted a reach of the moveable device is less than when in the basic positions; 
 sensing the position of at least one of the moveable device and the hydraulic actuator; 
 delivering hydraulic fluid at a pressure to the hydraulic actuator and pressurizing the hydraulic fluid at most to a predetermined maximum pressure; and 
 regulating the predetermined maximum pressure to be lower in the retracted position than in the basic positions based on the determined position. 
 
     
     
       17. The method according to  claim 16 , wherein the method further comprises:
 moving the moveable device to several positions such that the reach of the moveable device is dependent on the positions; and 
 regulating the predetermined maximum pressure on the basis of the reach.